The present invention relates generally to integrated circuit manufacturing equipment, and in particular to apparatus for cleaning wafer holders, such as chucks, in such equipment.
Manufacturing of integrated circuits requires a clean environment to control contaminates, which may come into contact with wafers and circuits. Contaminants may result in defective circuits. As a result, manufacturing takes place in clean rooms, which are essentially purified spaces with ultraclean air that isolates the circuit manufacturing from potential contaminants in ambient air. Potential contaminants include particles, metals, organic molecules, and the like. A clean room includes devices and procedures to ensure contaminant free manufacturing environment as much as possible. Discussions of clean room technologies can be found in MICROCHIP FABRICATION, Fourth Edition, Chap. 5, pages 87-132, by Peter Van Zant, herein incorporated by reference.
Particles can cause defects during the fabrication process leading to open or shorted circuitry. A conventional rule for acceptable particle size is one-half the feature size. Thus, as the feature size decreases then the acceptable particle size also decreases. One conventional method for removing particles from some wafer handling equipment is to shut off the fabrication process and manually clean the equipment. This method requires a significant shutdown time of the processing equipment. Moreover, if clean protocols are not strictly adhered to by the technician cleaning the equipment, then the wafer fabrication environment and wafer handling equipment may have more contaminants after the manual cleaning.
One particular step in the manufacturing process where particle contaminants may cause defects is during photolithography. Referring to FIG. 1, there is shown a partial view of a wafer 100 held on a wafer support 105 in a wafer exposure tool 106 such as a photolithography device. Exposure tool 106 is designed to exposure a planar top surface of the wafer to light 107. A contaminant particle 108 is positioned between the wafer and the support 105. The particle 108 causes the wafer 100 to bow as show at 109 such that it does not have a planar top surface. This results in the light 107 from exposure tool 106 not being focused on the top surface of the wafer at the bowed area 109. Accordingly, the exposure tool may not properly expose the wafer top surface. For example, the wafer could bow upward about 0.2 microns resulting improper exposure of this area of the wafer. This could result in defective resist formation and in defects in the subsequently formed structures on the wafer.
For the reasons stated above, for other reasons stated below, and for other reasons which will become apparent to those skilled in the art upon reading and understanding the present specification, there is a need in the art for improved integrated circuit manufacturing equipment and methods of manufacturing integrated circuits.
An embodiment of the present invention includes a wafer handler engaging device and a particle removal surface on the device. The particle removal surface removes particles from a wafer handler. In an embodiment, the wafer handler is a chuck. In an embodiment, the wafer handler is a spindle chuck. In an embodiment, the wafer handler engaging device includes an arm for moving the particle removal surface into contact with a face of a wafer handler. In an embodiment, the wafer handler engaging device includes a spin drive for rotating the particle removal surface relative to the arm. In an embodiment, the arm includes a joint. In an embodiment, the arm includes a fixed support and the joint pivots the particle removal surface relative to the fixed support. In an embodiment, the wafer handler engaging device includes a spin drive for rotating the particle removal surface. In an embodiment, the spin drive rotates the particle removal surface relative to the wafer handler. In an embodiment, a vacuum source is provided for removing the particle from the environment of the wafer handler. In an embodiment, pathways extend through the wafer handler engaging device and connect to the vacuum source, the pathways including ports at the particle removal surface. In an embodiment, the particle removal surface includes a ceramic. In an embodiment, the particle removal surface includes a brush.
An embodiment of the present invention includes a track system for handling and/or processing wafers. The track system includes a spindle chuck assembly and an automated spindle chuck cleaner capable of cleaning the spindle chuck assembly. In an embodiment, the spindle chuck assembly includes a wafer holding head, and the spindle chuck cleaner cleans the head. In an embodiment, the automated spindle chuck cleaner includes a ceramic surface that contacts the head to remove particles therefrom. In an embodiment, the automated spindle chuck cleaner includes a brush that contacts the head to remove particles therefrom.
An embodiment of the present invention includes a wafer processing system, which includes a spindle chuck, an automated spindle chuck cleaner, and an alignment and exposure device. In an embodiment, the alignment and exposure device is a stepper. In an embodiment, the alignment and exposure device is a step and scan device. In an embodiment, the alignment and exposure device is a scanner. In an embodiment, the spindle chuck includes a wafer holding head, and the spindle chuck cleaner cleans the head. In an embodiment, the automated spindle chuck cleaner includes a ceramic surface or a brush. In an embodiment, the automated spindle chuck cleaner includes a vacuum source that is adjacent the head to remove at least one particle therefrom. In an embodiment, the track unit includes a plurality of track devices, each including at least one spindle chuck.
An embodiment of the present invention includes a controller for controlling the wafer holder and the wafer holder cleaner. In an embodiment, the controller includes a processor and communicates with the elements of a wafer processing system. In an embodiment, the instructions for operation of the wafer processing system, including the wafer holder cleaner, are stored on a machine readable media. In an embodiment, the instructions include moving the cleaning surface into contact with the head and removing contaminants from the head.
An embodiment of the present invention includes methods for cleaning a wafer holder, such as a chuck. An embodiment includes moving the cleaning surface into contact with the head and removing contaminants from the head. An embodiment includes placing a wafer on a head of a spindle chuck, performing a fabrication process on the wafer, removing the wafer from the head, and automatically cleaning contaminants from the head. An embodiment includes returning the wafer to head.
Further embodiments of the present invention will be apparent to one of ordinary skill upon reading the present disclosure.